This invention relates to medical apparatus in general, and more particularly to anatomical visualization systems.
Many medical procedures must be carried out at an interior anatomical site which is normally hidden from the view of the physician. In these situations, the physician typically uses some sort of scanning device to examine the patient""s anatomy at the interior site prior to, and in preparation for, conducting the actual medical procedure. Such scanning devices typically include CT scanners, MRI devices, X-ray machines, ultrasound devices and the like, and essentially serve to provide the physician with some sort of visualization of the patient""s interior anatomical structure prior to commencing the actual medical procedure. The physician can then use this information to plan the medical procedure in advance, taking into account patient-specific anatomical structure. In addition, the physician can also use the information obtained from such preliminary scanning to more precisely identify the location of selected structures (e.g., tumors and the like) which may themselves be located within the interior of internal organs or other internal body structures. As a result, the physician can more easily xe2x80x9czero inxe2x80x9d on such selected structures during the subsequent medical procedure. Furthermore, in many cases, the anatomical structures of interest to the physician may be quite small and/or difficult to identify with the naked eye. In these situations, preliminary scanning of the patient""s interior anatomical structure using high resolution scanning devices can help the physician locate the structures of interest during the subsequent medical procedure.
In addition to the foregoing, scanning devices of the sort described above are frequently also used in purely diagnostic procedures.
In general, scanning devices of the sort described above tend to generate two-dimensional (i.e., xe2x80x9c2-Dxe2x80x9d) images of the patient""s anatomical structure. In many cases, the scanning devices are adapted to provide a set of 2-D images, with each 2-D image in the set being related to every other 2-D image in the set according to some pre-determined relationship. For example, CT scanners typically generate a series of 2-D images, with each 2-D image corresponding to a specific plane or xe2x80x9cslicexe2x80x9d taken through the patient""s anatomical structure. Furthermore, with many scanning devices, the angle and spacing between adjacent image planes or slices is very well defined, e.g., each image plane or slice may be set parallel to every other image plane or slice, and adjacent image planes or slices may be spaced a pre-determined distance apart. By way of example, the parallel image planes might be set 1 mm apart.
In a system of the sort just described, the physician can view each 2-D image individually and, by viewing a series of 2-D images in proper sequence, can mentally generate a three-dimensional (i.e., xe2x80x9c3-Dxe2x80x9d) impression of the patient""s interior anatomical structure.
Some scanning devices include, as part of their basic system, associated computer hardware and software for building a 3-D database of the patient""s scanned anatomical structure using a plurality of the aforementioned 2-D images. For example, some CT and MRI scanners include such associated computer hardware and software as part of their basic system. Alternatively, such associated computer hardware and software may be provided independently of the scanning devices, as a sort of xe2x80x9cadd-onxe2x80x9d to the system; in this case, the data from the scanned 2-D images is fed from the scanning device to the associated computer hardware and software in a separate step. In either case, a trained operator using the scanning device can create a set of scanned 2-D images, assemble the data from these scanned 2-D images into a 3-D database of the scanned anatomical structure, and then generate various additional images of the scanned anatomical structure using the 3-D database. This feature is a very powerful tool, since it essentially permits a physician to view the patient""s scanned anatomical structure from a wide variety of different viewing positions. As a result, the physician""s understanding of the patient""s scanned anatomical structure is generally greatly enhanced.
In addition, these systems often include software and/or hardware tools to allow measurements to be made, e.g., the length of lines drawn on the image may be calculated.
While the 2-D slice images generated by the aforementioned scanning devices, and/or the 3-D database images generated by the aforementioned associated computer hardware and software, are generally of great benefit to physicians, certain significant limitations still exist.
For one thing, with current systems, each scanned 2-D slice image is displayed as a separate and distinct image, and each image generated from the 3-D database is displayed as a separate and distinct image. Unfortunately, physicians can sometimes have difficulty correlating what they see on a particular scanned 2-D slice image with what they see on a particular image generated from the 3-D database.
For another thing, in many situations a physician may be viewing images of a patient""s scanned anatomical structure in preparation for conducting a subsequent medical procedure in which a prosthetic device must be fitted in the patient. In these situations it can be relatively difficult and/or time-consuming for the physician to accurately measure and record all of the anatomical dimensions needed for proper sizing of the prosthetic device to the patient. By way of example, in certain situations a patient may develop an abdominal aortic aneurysm (xe2x80x9cAAAxe2x80x9d) in the vicinity of the aorta""s iliac branching, and replacement of the affected vascular structure may be indicated. In this case it is extremely important for the physician to determine, for each affected portion of blood vessel, accurate length and cross-sectional dimensions to ensure proper sizing of the replacement prosthesis to the patient. Such anatomical measurement and recordation can be difficult and/or time-consuming with existing visualization systems. This has proven to be particulary true when dealing with anatomical structures which have a tortuous path or branching structure, e.g., blood vessels.
Accordingly, one object of the present invention is to provide an improved anatomical visualization system wherein a scanned 2-D slice image can be appropriately combined with an image generated from a 3-D database so as to create a single composite image.
Another object of the present invention is to provide an improved anatomical visualization system wherein a marker can be placed onto a 2-D slice image displayed on a screen, and this marker will be automatically incorporated, as appropriate, into a 3-D computer model maintained by the system, as well as into any other 2-D slice image data maintained by the system.
Still another object of the present invention is to provide an improved anatomical visualization system wherein a margin of pre-determined size can be associated with a marker of the sort described above, and further wherein the margin will be automatically incorporated into the 3-D computer model, and into any other 2-D slice image data, in association with that marker.
Yet another object of the present invention is to provide an improved anatomical visualization system wherein the periphery of objects contained in a 3-D computer model maintained by the system can be automatically identified in any 2-D slice image data maintained by the system, wherein the periphery of such objects can be highlighted as appropriate in 2-D slice images displayed by the system.
And another object of the present invention is to provide an improved method for visualizing anatomical structure.
Another object of the present invention is to provide an improved anatomical visualization system wherein patient-specific anatomical dimensions may be easily and quickly determined.
And another object of the present invention is to provide an improved anatomical visualization system wherein an appropriate set of scanned 2-D images can be assembled into a 3-D database, computer models of patient-specific anatomical structures can be extracted from the information contained in this 3-D database, and these computer models can then be used to calculate desired patient-specific anatomical dimensions.
Still another object of the present invention is to provide an improved anatomical visualization system which is particularly well adapted to determine patient-specific anatomical dimensions for structures which have a branching configuration, e.g., blood vessels.
Yet another object of the present invention is to provide an improved method for calculating patient-specific anatomical dimensions using appropriate scanned 2-D image data.
These and other objects are addressed by the present invention, which comprises a visualization system comprising a first database that comprises a plurality of 2-D slice images generated by scanning a structure. The 2-D slice images are stored in a first data format. A second database is also provided that comprises a 3-D computer model of the scanned structure. The 3-D computer model comprises a first software object that is defined by a 3-D geometry database. Means are provided for inserting a second software object into the 3-D computer model so as to augment the 3-D computer model. The second software object is also defined by a 3-D geometry database, and includes a planar surface. Means for determining the specific 2-D slice image associated with the position of the planar surface of the second software object within the augmented 3-D computer model are provided in a preferred embodiment of the invention. Means are also provided for texture mapping the specific 2-D slice image onto the planar surface of the second software object. Display means are provided for displaying an image of the augmented 3-D computer model so as to simultaneously provide a view of the first software object and the specific 2-D slice image texture mapped onto the planar surface of the second software object.
In one alternative embodiment of the present invention, a visualization system is provided comprising a first database comprising a plurality of 2-D slice images generated by scanning a structure. The 2-D slice images are again stored in a first data format. A second database comprising a 3-D computer model of the scanned structure is also provided in which the 3-D computer model comprises a first software object that is defined by a 3-D geometry database. Means are provided for selecting a particular 2-D slice image the first database. Means are also provided for inserting a second software object into the 3-D computer model so as to augment the 3-D computer model. The second software object is defined by a 3-D geometry database, and also includes a planar surface. In this alternative embodiment however, the second software object is inserted into the 3-D computer model at the position corresponding to the position of the selected 2-D slice image relative to the scanned structure. Means for texture mapping the specific 2-D slice image onto the planar surface of the second software object are also provides. Means are provided for displaying an image of the augmented 3-D computer model so as to simultaneously provide a view of the first software object and the specific 2-D slice image texture mapped onto the planar surface of the second software object.
In each of the foregoing embodiments of the present invention, the 3-D geometry database may comprise a surface model. Likewise, the system may further comprise means for inserting a marker into the first database, whereby the marker will be automatically incorporated into the second database, and further wherein the marker will be automatically displayed where appropriate in any image displayed by the system. Also, the system may further comprise a margin of pre-determined size associated with the marker. Additionally, the system may further comprise means for automatically determining the periphery of any objects contained in the second database and for identifying the corresponding data points in the first database, whereby the periphery of such objects can be highlighted as appropriate in any image displayed by the system. Often, the scanned structure will comprise an anatomical structure.
The present invention also comprises a method for visualizing an anatomical structure.
In yet another form of the present invention, the visualization system may incorporate means for determining patient-specific anatomical dimensions using appropriate scanned 2-D image data. More particularly, the visualization system may include means for assembling an appropriate set of scanned 2-D images into a 3-D database, means for extracting computer models of patient-specific anatomical structures from the information contained in the 3-D database, and means for calculating desired patient-specific anatomical dimensions from the aforementioned computer models.
The present invention also comprises a method for calculating patient-specific anatomical dimensions using appropriate scanned 2-D image data. In one form of the present invention, the method comprises the steps of (1) assembling an appropriate set of scanned 2-D images into a 3-D database; (2)extracting computer models of patient-specific anatomical structures from the information contained in the 3-D database, and (3)calculating desired patient-specific anatomical dimensions from the aforementioned computer models.
In a more particular form of the present invention, the visualization system is particularly well adapted to determine patient-specific anatomical dimensions for structures which have a branching configuration, e.g., blood vessels. In this form of the invention, the visualization system is adapted to facilitate (1)assembling an appropriate set of scanned 2-D images into a 3-D database; (2)segmenting the volumetric data contained in the 3-D database into a set of 3-D locations corresponding to the specific anatomical structure to be measured; (3) specifying, for each branching structure contained within the specific anatomical structure of interest, a branch line in the volumetric data set that uniquely indicates that branch structure, with the branch line being specified by selecting appropriate start and end locations on two of the set of scanned 2-D images; (4)calculating, for each branching structure contained within the specific anatomical structure of interest, a centroid path in the volumetric data set for that branching structure, with the centroid path being determined by calculating, for each scanned 2-D image corresponding to the branch line, the centroid for the branch structure contained in that particular scanned 2-D image; (5)applying a curve-fitting algorithm to the centroid paths determined above so as to supply data for any portions of the anatomical structure which may lie between the aforementioned branch lines, and for xe2x80x9csmoothing outxe2x80x9d any noise that may occur in the system; and (6) applying known techniques to the resulting space curves so as to determine the desired anatomical dimensions.